• Journal of the Korean Ceramic Society
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• v.55 no.4
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• pp.344-351
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• 2018

The effects of bond coat species on the growth behavior of thermally grown oxide (TGO) layer in thermal barrier coatings (TBCs) was investigated through furnace cyclic test (FCT). Two types of feedstock powder with different particle sizes and distributions, AMDRY 962 and AMDRY 386-4, were used to prepare the bond coat, and were formed using air plasma spray (APS) process. The top coat was prepared by APS process using zirconia based powder containing 8 wt% yttria. The thicknesses of the top and bond coats were designed and controlled at 800 and $200{\mu}m$, respectively. Phase analysis was conducted for TBC specimens with and without heat treatment. FCTs were performed for TBC specimens at $1121^{\circ}C$ with a dwell time of 25 h, followed by natural air cooling for 1 h at room temperature. TBC specimens with and without heat treatment showed sound conditions for the AMDRY 962 bond coat and AMDRY 386-4 bond coat in FCTs, respectively. The growth behavior of TGO layer followed a parabolic mode as the time increased in FCTs, independent of bond coat species. The influences of bond coat species and heat treatment on the microstructural evolution, interfacial stability, and TGO growth behavior in TBCs are discussed.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.33-39
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• 2010

The electrolytic reduction of a spent oxide fuel involves a liberation of the oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. Accordingly, it is essential to choose the optimum material for the processing equipment that handles the high molten salt. In this study, hot corrosion studies were performed on bare as well as coated superalloy specimens after exposure to lithium molten salt at $675^{\circ}C$ for 216 h under an oxidizing atmosphere. The IN713LC superalloy specimens were sprayed with an aluminized NiCrAlY bond coat and then with an $Y_2O_3$ top coat. The bare superalloy reveals an obvious weight loss due to spalling of the scale by the rapid scale growth and thermal stress. The chemical and thermal stability of the top coat has been found to be beneficial for increasing to the corrosion resistance of the structural materials for handling high temperature lithium molten salts.